I'm Curious as to how this endevour ended up, because I have a TR-500FL for sale and I was thinking of replacing the pickups, but I don't know what I can put in those huge soapbar slots. Any ideas? You can view the pickups on my Signature.

You can go the Bartolini site, and they have the measurements for all of the pickups. Grab a ruler and measure the ones on the bass. The Bart site had a few sets that matched the size.

I never did the project in the end. I put the bass in the shop, got the wiring fixed, setup done, and a few other fixes here and there. Now, it's killer, it's my main fretted bass. I got a fretless Essex Jazz for my fretless needs.